The Common Pleco or Plecostomus is a freshwater tropical fish belonging to the Armored Catfish family (Loricariidae). The nocturnal fish is extremely popular in the aquarium hobby for its ability to clean tanks of algae. There are a number of species that are sold on the market under the name Common Pleco, including Hypostomus plecostomus, Hypostomus punctatus, Liposarcus multiradiatus, and Liposarcus pardalis.

The fish are commonly sold when they are 2 - 3 in (5 - 8 cm) and while there is some variety among the species, the Common Pleco will grow to an adult size in excess of 8 - 12 in (20 - 30 cm), sometimes in less than a year. Mainly herbivorous, they can be fed dried algae pellets and wafers or be fed fresh green vegetables such as spinach, lettuce, and cucumbers. They will occasionally feed on dead fish or attach themselves to the sides of large bodied fish such as the goldfish.